The present invention relates to a wire connection structure for connecting an operation wire to a member, (to which the operation wire is connected,) for an endoscope.
As an operation wire for an endoscope, a stranded wire is generally used. The stranded wire is a wire formed by twisting a plurality of thin wires so that it does not have a bending property. When such a stranded wire is connected to another member, for example, an end of the stranded wire is inserted into a hole formed in the member, with which the stranded wire is connected, and then, the end of the stranded wire is silver brazed or soldered thereto.
When the stranded wire is silver brazed, the portions of the stranded wire and the connected member should be heated up to 600xc2x0 C. In order to heat the portion to be brazed, a small burner or the like is used as a heating tool. Due to difference of heat capacity, the portion of the stranded wire which is not inserted in the connected member tends to be heated easily in comparison with the portion of the wire inserted in the connected member. Therefore, to the portion of the stranded wire that is to be brazed, the brazing silver is hardly applied, while, the portion of the stranded wire that is not brazed is heated and the brazing silver may be applied thereto. In such a case, the portion hardened by the brazing silver may be longer than a designed length, or the operation wire (i.e., the stranded wire) may be oxidized and the strength may be weakened.
If the stranded wire is to be soldered to the connected member, the fixing strength is inherently weak, and even a small amount of residual flux remains, the soldered portion may be broken off. Therefore, in this case, the flux should be completely cleaned, which is very troublesome.
It is therefore an object of the invention to provide an improved connection structure for connecting an operation wire with a member to be connected at stable strength with a simple and reliable process.
For the above object, according to the invention, there is provided a connection structure for connecting a stranded operation wire and a connection member of an endoscope, in which an end of the stranded operation wire is formed to be an integrally fixed portion where a plurality of strands constituting the stranded operation wire are fixed to each other, and a hole is formed on the connection member, at least the integrally fixed portion of the stranded operation wire being inserted in the hole, the connection member being plastically deformed such that the connection member and the stranded operation wire located in the hole being engaged with each other.
Since the tip of the stranded wire is integrally fixed, removal of the tip portion through the plastically deformed connection member is prevented. Accordingly, the operation wire can be firmly secured to the connection member.
In one example, a portion of the wire inserted in the hole includes the integrally fixed portion and a stranded wire portion that is not integrally fixed, a position where the connection member is plastically deformed corresponding to the stranded wire portion next to the integrally deformed portion.
In this case, the deformed portion of the connection member is well pushed into the stranded wire portion.
Alternatively or optionally, a position where the connection member is plastically deformed corresponds to the integrally deformed portion.
Since the integrally fixed portion hardly deforms and therefore it prevents the removal of the operation wire through the deformed portion of the connection member.
The stranded operation wire may be an operation wire of a treatment accessory of the endoscope. Alternatively, the stranded operation wire may be a operation wire for moving a bendable portion of a main body of the endoscope.
In particular, an engaging protrusion having a through hole is provided on an inner surface of the bendable portion. The operation wire is provided with an engaging member, and the engaging member is inserted through the through hole formed on the protrusion from a distal end side of the endoscope to a proximal end side.
With this structure, the wire and the connection member are firmly connected, and the engaging member is prevented from passing through the hole formed on the engaging protrusion. Therefore, when the wire is drawn at the proximal end of the endoscope, the bendable portion is bent due to the drawing force of the operation wire.